Virtual world subgroup determination and segmentation for performance scalability

ABSTRACT

A system and method of decreasing server loads and, more particularly, to decrease server load by automatically determining subgroups based on object interactions and computational expenditures. The system includes a plurality of servers; a subgroup optimization module configured to segment a plurality of objects into optimal subgroups; and a server transfer module configured to apportion one or more of the optimal subgroups between the plurality of servers based on a load of each of the plurality of servers. The method includes determining a relationship amongst a plurality of objects; segmenting the objects into optimized subgroups based on the relationships; and apportioning the optimized subgroups amongst a plurality of servers based on server load.

FIELD OF THE INVENTION

The invention generally relates to providing a system and method of useto decrease server load and, more particularly, to decrease server loadby automatically determining subgroups based on object interactions andcomputational expenditures.

BACKGROUND OF THE INVENTION

Virtual universes (VUs) are computer-based simulations of the real worldwhere users interact with one another using online identities. Theseonline identities, known as avatars, can be chosen by a user tographically represent himself within the VU in a human-like form.

A VU is similar in many respects to the real world. VU's can havedifferent geographical locations, time metrics, and assets that may beused similarly to those used in the real world. A VU stores all of thisinformation, including avatar data, on a number of servers. In the past,each server has represented a geographic location within the VU and hasalso included all of the data for the avatars within the VU's geographiclocation. Presently, millions of users have participated in VUs and anumber of different geographic locations have been created requiringnumerous servers to handle the load.

The problem that arises with VUs is that it is difficult to control howmuch load is on any given server. For example, there may be thousands ofavatars in one geographic location and only ten avatars in anotherlocation. This causes the server with thousands of avatars to overloadand the server with only ten avatars to be underutilized. When a serverbecomes overloaded, the avatar interactions handled by the overloadedserver appear slower than normal to the user. Depending on the degree ofoverload, the user will become frustrated with the slow speed and leavethe VU. This results in fewer users and affects the amount of incomethat can be generated within the VU.

Accordingly, there exists a need in the art to overcome the deficienciesand limitations described hereinabove.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a system for reducing server loadsis provided. The system comprises a plurality of servers, a subgroupoptimization module configured to segment a plurality of objects intooptimal subgroups, and a server transfer module configured to apportionone or more of the optimal subgroups between the plurality of serversbased on a load of each of a plurality of servers.

In another aspect of the invention, a method comprises reducing serverload by determining a relationship amongst a plurality of objects;segmenting the objects into optimized subgroups based on therelationships; and apportioning the optimized subgroups amongst aplurality of servers based on server load.

In another aspect of the invention, a method for deploying anapplication for reducing server loads is provided. The computer methodcomprises a computer infrastructure being operable to: segment aplurality of objects into a plurality of subgroups; and transfer one ormore of the subgroups from a first server to at least a second serverbased on a determined load of the first server and the at least secondserver.

In yet another aspect of the invention, a computer program productcomprises a computer usable medium having readable program code embodiedin the medium. The computer program product includes at least onecomponent to: determine a relationship amongst a plurality of objects;segment the objects into optimized subgroups based on the relationships;and apportion the optimized subgroups amongst a plurality of serversbased on server load.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIG. 1 shows an illustrative environment for implementing the steps inaccordance with the invention;

FIG. 2 shows a block diagram for implementing aspects of the subgroupoptimization module and the server transfer module in accordance withthe invention;

FIG. 3 shows a table illustrating hypothetical avatar transactions andinteraction costs based in part on a transaction look-up table inaccordance with the invention;

FIG. 4 shows a graph illustrating communication costs, computationcosts, and a segmentor in accordance with the invention;

FIG. 5 shows the illustrative graph from FIG. 4 after the graph issegmented by the segmentor in accordance with the invention;

FIG. 6 shows the server transfer module transferring optimal subgroupsbetween servers in accordance with the invention;

FIG. 7 shows the servers from FIG. 6 after the server transfer modulehas transferred optimal subgroups between servers in accordance with theinvention; and

FIG. 8 shows an illustration of an overload detection system and servertransfer module in accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is directed to providing a system and method of use todecrease server load and, more particularly, to decrease server load byautomatically determining subgroups based on object interactions andcomputational expenditures. By implementing this system and method ofuse, it is possible to automatically determine how many resources areused by the server within the VU, how many resources are used by theserver external to the VU, and how different avatars and assets withinthe VU interact with one another. Based on these determinations, itbecomes possible to estimate how much load is on a server at a givenpoint. It also becomes possible to logically distribute the loadsbetween one or more servers by grouping together avatars and/or assetsthat share common interactions. Typically this grouping allows avatarsand assets that have some commonality to be located on the same server.By being grouped on the same server, avatars can more efficiently usetheir resources and communicate with other avatars within theirsubgroup, as well as being able to continue interacting with avatarsexternal to their subgroup. Moreover, assets throughout the VU may alsobe more efficiently utilized by being grouped together with other assetssharing a commonality, or with avatars associated with the asset.Additional benefits may include:

-   -   (i) Improved VU performance;    -   (ii) Improved resident satisfaction;    -   (iii) Protection against VU crash; and    -   (iv) Protection against malicious mob actions that attempt to        slow the VU.

By using this system and method of use for optimizing server loads,degradation within the VU from server overload is limited. As such,users are able to continue to interact seamlessly.

System Environment

FIG. 1 shows an illustrative environment 10 for managing the processesin accordance with the invention. To this extent, the environment 10includes a computer infrastructure 20 that can perform the processesdescribed herein. In particular, the computer infrastructure 20 includesa computing device 24 that comprises a management system 35, which makesthe computing device 24 operable to detect optimal alignment betweensubgroups via a subgroup optimization module 26 and transfer the optimalsubgroups between one or more servers 65 via a server transfer module 28in accordance with the invention, e.g., process described herein. Thecomputing device 24 includes a processor 30, a memory 34, aninput/output (I/O) interface 40, and a bus 50. The memory 34 can includelocal memory employed during actual execution of program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution. Further, the computingdevice 24 is in communication with an external I/O device/resource 52and a storage system 60. The external I/O device/resource 52 may bekeyboards, displays, pointing devices, etc.

In general, the processor 30 executes computer program code, which isstored in memory 34 and/or storage system 60. While executing computerprogram code, the processor 30 can read and/or write data to/from memory34, storage system 60, and/or I/O interface 40. The bus 50 provides acommunications link between each of the components in the computingdevice 24. The I/O device 52 can comprise any device that enables anindividual to interact with the computing device 24 or any device thatenables the computing device 24 to communicate with one or more othercomputing devices using any type of communications link.

The computing device 24 can comprise any general purpose computingarticle of manufacture capable of executing computer program codeinstalled thereon (e.g., a personal computer, server, handheld device,etc.). However, it is understood that the computing device 24 is onlyrepresentative of various possible equivalent computing devices that mayperform the processes described herein. To this extent, in embodiments,the functionality provided by computing device 24 can be implemented bya computing article of manufacture that includes any combination ofgeneral and/or specific purpose hardware and/or computer program code.In each embodiment, the program code and hardware can be created usingstandard programming and engineering techniques, respectively.

Similarly, the computer infrastructure 20 is only illustrative ofvarious types of computer infrastructures for implementing theinvention. For example, in embodiments, the computer infrastructure 20comprises two or more computing devices (e.g., a server cluster) thatcommunicate over any type of communications link, such as a network, ashared memory, or the like, to perform the process described herein.Further, while performing the processes described herein, one or morecomputing devices in the computer infrastructure 20 can communicate withone or more other computing devices external to computer infrastructure20 using any type of communications link. The communications link cancomprise any combination of wired and/or wireless links; any combinationof one or more types of networks (e.g., the Internet, a wide areanetwork, a local area network, a virtual private network, etc.); and/orutilize any combination of transmission techniques and protocols.

Moreover, it should be understood that the computer infrastructure maybe supported, maintained, provided, and deployed by a service provideron a fee and/or subscription basis. Still yet, any of the components ofthe present invention could be deployed, managed, serviced, etc., by aservice provider who offers to decrease server load by automaticallydetermining subgroups based on object interactions and computationalexpenditures.

Processes of the Invention

FIG. 2 is a block diagram of the invention. FIG. 2 may equally representa high-level flow diagram or process flow chart implementing steps ofthe invention having the infrastructure of FIG. 1. In the case of a flowdiagram, the steps of FIG. 2 may be implemented and executed from eithera server, in a client server relationship, or they may run on a userworkstation with operative information conveyed to the user workstationto determine optimal subgroups to decrease server load. Additionally,the invention can take the form of an entirely hardware embodiment, anentirely software embodiment or an embodiment containing both hardwareand software elements.

In an embodiment, the invention is implemented in software, whichincludes but is not limited to firmware, resident software, microcode,etc. Furthermore, the invention can take the form of a computer programproduct accessible from a computer-usable or computer-readable mediumproviding program code for use by or in connection with a computer orany instruction execution system. The software and/or computer programproduct can be implemented in the environment of FIG. 1, as should beunderstood and capable of implementation by those of skill in the art.For the purposes of this description, a computer-usable or computerreadable medium can be any apparatus that can contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device) or apropagation medium. Examples of a computer-readable medium include asemiconductor or solid state memory, magnetic tape, a removable computerdiskette, a random access memory (RAM), a read-only memory (ROM), arigid magnetic disk and an optical disk. Current examples of opticaldisks include compact disk—read only memory (CD-ROM), compactdisk—read/write (CD-R/W) and DVD.

FIG. 2 shows a subgroup optimization module 26, in combination with aserver transfer module 28 and an overload detection system 170 which isdiscussed in further detail with reference to FIGS. 3-8, avatars andassets in a VU are grouped into optimal subgroups by the subgroupoptimization module 26. When an avatar participates in a VU, the avatarforms a number of relationships, or interactions 101, 102, 103 . . .i+1, with one or more additional avatars or assets in the VU. Theseinteractions 101, 102, 103 . . . i+1 are analyzed and a result isproduced by a communication cost estimator 120. Additionally, objectcomputation consumption 126 and server computation consumption 128 areanalyzed and a result is produced by the computation cost estimator 130based off of the object computation consumption 126 and/or the servercomputation consumption 128. The result from the communication costestimator 120 is combined with the result from the computation costestimator 130 to obtain a value. A multiplier 140 may or may not beapplied to this value. The value is then analyzed by a segmentor 160,which optimally segments avatars and/or assets into subgroups based ontheir communications and computational resources. After the segmentor160 creates one or more subgroups, the subgroups are transferred by theserver transfer module 28 to a different server, or alternatively thesubgroups may remain on the original server.

The process outlined above may be done periodically according to apredetermined schedule. However, if server load reaches, or is about toreach, a predicted point, then an overload detection system 170 may beused to reallocate server load without using the subgroup optimizationmodule 28. In this case, subgroup determination is performed by theoverload detection system 170 and subgroups are transferred by theserver transfer module 28 to different servers, or alternatively thesubgroups may remain on the original server.

FIG. 3 further illustrates the process of estimating the communicationcost used in FIG. 2. The interactions 101, 102, 103 . . . i+1 in FIG. 2may be current or old interactions and/or relationships. Theinteractions may include, but are not limited to, “real world”geographic location, friend or buddy lists, corporate or organizationalinteractions, shared interests, shared inventory, recent interactions,and other mechanisms that would link one avatar to another avatar suchas real-time interactions, e.g., chatting via audio and instant messagecommunication. Each interaction 101, 102, 103 . . . i+1 is analyzed andinteractions 101, 102, 103 . . . i+1 that meet predetermined criteriaare assigned a unit value 210 when they occur. The unit value 210 may bestored in a number of data structures including an array, list, ortable; for purposes of illustration, a table will be used as the datastructure in this example. Unit values 210 associated with aninteraction 101, 102, 103 . . . i+1 may be applied to avatars and/orassets in the VU. These unit values 210 may vary depending on the typeof interaction 220 and when the interaction 101, 102, 103 . . . i+1occurred. In one embodiment, interactions 101, 102, 103 . . . i+1 may beaccrued over a time window that is chosen by the VU administrator tooptimize the rate at which communication cost values change. Unit values210 may then be used to establish an interaction cost 230 for eachinteraction 101, 102, 103 . . . i+1. For example, avatars or assets thatinteract more frequently may obtain a higher interaction cost 230,whereas infrequent interactions 101, 102, 103 . . . i+1 may result in alower interaction cost 230.

For example, FIG. 3 illustrates how avatar #13 interacts with otheravatars and how interactions 101, 102, 103 . . . i+1 are stored in atransaction table. Once an interaction is stored, a look-up table may beconsulted to give a certain unit value 210 to each interaction. Unitvalues 210 may vary depending on the importance of the interaction, thelength of the interaction, when the interaction occurred, as well as anumber of alternative factors. Alternatively, each interaction may havethe same unit value 210 or no unit value 210 at all.

Unit values 210 may also be assigned to interactions between an avatarand an asset. For example, if an avatar #13 frequently uses an assetwithin a VU, such as a car #61, then a unit value 210 may be assignedeach time the avatar drives car #61. This interaction may be kept in thetransaction table for avatar #13, or in the transaction table for car#61. In alternative embodiments, the interaction may be kept in thetransaction tables for both avatar #13 and car #61.

Unit values 210 may also be assigned to interactions between assets. Forexample, if avatar #13 frequently drives car #61 to and from a virtualcoffee store #2, then a transaction cost is associated between avatar#13 and coffee store #2, as well as between car #61 and coffee store #2.Therefore, assets may interact with one another.

Once a unit value 210 is determined, that unit value 210 is applied tothe interaction to determine an interaction cost 230 for thatinteraction. If an interaction cost 230 is high enough, then the servertransfer module 28 may be triggered.

Once an interaction cost 230 for an interaction is determined, thatinteraction cost 230 is combined with other interaction costs 230involving the same avatar or asset (if such interaction costs 230 exist)and a communication cost estimator 120 is used to estimate the totalcommunication cost, or communication load. For example, in FIGS. 3 and4, avatar #13 has bumped into avatar #111 within the last four days andalso shares 90% of his inventory with avatar #111. These interactioncosts 230 would be combined by the communication cost estimator 120 toform an estimated communication cost, or weighted link, 325 (See FIG. 4)between avatar #13 and avatar #111. If it was also determined thatavatar #111 is a member of corporation A and/or belongs to club B thenthe weighted link 325 between avatar #13 and avatar #111 would becomestronger. Conversely, if avatar #13 and avatar #111 had only bumped intoeach other within the last 3 days, then the weighted 325 link betweenavatar #13 and avatar #111 would not be as strong. A similar approach istaken when estimating communication costs for an asset. This approachcan be represented using the hypothetical graph in FIG. 4, wherein eachavatar or assets is represented by a node 305 which has a weighted link,or edge, 325 to one or more different avatars. Each weighted link, oredge, 325 between two nodes 305 represents the estimated communicationcost.

Referring back to FIG. 2, while the avatar is interacting in the VU, itis using server resources. These resources may include different assetsthat the avatar has acquired, or details about the avatar. The totalserver resources consumed through interactions between assets and/oravatars are combined in a predetermined way to obtain an objectcomputation consumption 126. This object computation consumption 126 isthen used by the computation cost estimator 130 to determine a totalcomputation cost, or computation load, on a server 65. For example, inone embodiment, an object computation cost 126 may be assigned to eachavatar and asset in the VU. This object computation cost 126 may bemeasured and accrued over time such that a running average is kept,where the running average is represented by the computations per unittime that the avatars or assets have consumed. Avatars that movefrequently, change appearance frequently, or perform numerous gestures,or other computational intensive actions, may accrue a largercomputation cost. The time window in which the running average isperformed can be parameterized by the VU administrator for optimalperformance. Generally, long time windows may result in slower changesto computation cost values, while shorter time windows may result inmore rapid changes to computation cost values. The object computationconsumption 126 is used to estimate the computation cost, or computationload, on the server 65.

In a further embodiment, server computation consumption 128 may be usedin addition to object computation consumption 126 to estimate thecomputation cost. Server computation consumption 128 includes resourcesthat are used external to the VU, whereas resources used by the avataror asset would be internal to the VU. External resources that may beincluded in determining the server computation consumption 128 includerunning processes external to the VU but on the same server, such asfile system indexing processes, user terminals, file transfers, etc.These server computation consumptions 128 affect how many CPU cycles andhow much memory is available on a server.

In an embodiment, object computation costs 126 and server computationcosts 128 may be estimated using the processes described above. Thesecosts may be combined in a predetermined way via a computation costestimator 130. The computation cost estimator 130 assigns the resultfrom the combination to the avatar as the avatar's total computationcost or to the asset as the asset's total computation cost. This can berepresented using the hypothetical graph in FIG. 4, wherein each edge325 is an estimated communication cost associated with an avatar, andeach node 305 is an estimated computation cost.

In another embodiment, the communication cost and the computation costmay be combined as a function of one another to determine the serverload time. The server load time is representative of how tightly linkedtogether one or more avatars and/or assets are and how much one or moreof the avatars and/or assets are consuming in total resources. Based onthese determinations, a segmentor 160 will determine an optimalalignment to group avatars together. The segmentor 160 considers anumber of factors in making this determination. For example, thesegmentor 160 may try to group together avatars that interact frequently(i.e., have high communication costs). In one embodiment, usersinteracting in real-time by chatting or engaging in physical activities,such as virtual tennis, may be grouped together. By grouping theseavatars and assets together, the avatars and assets will remain on thesame server 65. This allows the avatar's interactions 101, 102, 103 . .. i+1 to be faster than if the avatars and assets were on differentservers 65 or in different groups. Alternatively, the optimal alignmentmay be to have unequal server loads on the servers 65.

In a further embodiment, optimal alignment may be obtained by applyingan optional multiplier 140 to the result obtained from the communicationcost estimator and the computation cost estimator. The multiplier 140may act as a way to increase or decrease the value that is used by thesegmentor 160 and server transfer module 28 in determining optimalserver load. For example, in one embodiment an avatar or asset mayobtain a multiplier 140 because of frequent interactions 101, 102, 103 .. . i+1 within the VU, by paying for a premium membership, or otherpredetermined methods of reaching an elevated status. This multiplier140 is applied to the combined estimated communication costs andestimated computation costs such that the multiplier 140 causes thecombined estimated communication costs and estimated computation coststo appear to have a higher load, compared to its actual load. Thisheightened calculated load is then used by the segmentor 160 whendetermining optimal subgroups and where to place the subgroups withinthe multitude of servers 65. The multiplier 140 may provide a preferenceto one subgroup over another when transmitting subgroups to differentservers 65. The multiplier 140, for example, may result in a preferredsubgroup being relocated to a faster server, a server with a lower load,etc., in order to maximize the user's VU experience.

In alternate embodiments, avatars and/or assets in a group having amember with a multiplier 140 may be grouped on the same server accordingto their multiplier value, whereas avatars and/or assets with no groupmember having a multiplier 140 may be grouped on a different server.Different embodiments may allow the multiplier value to vary dependingon user status or other outside factors.

FIG. 4 graphically represents portions of FIG. 2 using a series of edges325 and nodes 305 to represent a graph. The edges 325 in the graphrepresent the communication costs between avatars. The stronger the edge325 between avatars, the stronger the communication cost as representedby the thicker lines. The nodes 305 in the graph represent thecomputational cost for an avatar whereby the nodes 305 in thisillustrative graph are labeled according to an avatar identification.Once the segmentor 160 determines the optimal way to group avatarstogether, the segmentor 160 will segment one or more avatars into anoptimal grouping. Each subgroup 340, 350 is then placed on a respectiveserver via the server transfer module 28. In one embodiment, this may bedone as a function of how much load is already on the server and howmuch load is on other servers 65.

Further embodiments may also be explained using FIG. 4. In oneembodiment, instead of having each node represent an avatar, each nodemay alternatively represent an asset. Therefore, the edges between theassets indicate the strength of the communication costs between theassets. The stronger the communication cost between two assets, thethicker the line in the graph.

Other embodiments may include nodes within the graph that arerepresented by a plurality of intermingled avatars and assets. Forexample, two avatars A13 and A10 may both share the same desk A111 in avirtual classroom, only on alternating days. Therefore, both avatars A13and A10 have relatively strong communication costs with the desk A111,which are represented by the edges in the graph. However, avatar A13 andA10 may have little if any interactions with each other. Therefore,avatars A13 and A10 may be grouped together based on each avatar'sinteractions via the desk A111, i.e., via an asset.

FIG. 5 illustrates how the different subgroups 340, 350 in FIG. 4 areseparated prior to being transferred by the server transfer module 28.More specifically, the segmentor 160 in FIG. 4 has already optimallydetermined that certain nodes should be grouped together as a result oftheir communication costs and computation costs. Based on thisdetermination, the segmentor 160 splits the nodes into two optimalsubgroups 340, 350. These optimal subgroups are illustrated in theexample in FIG. 5. In this example, the segmentor 160 determined oneoptimal subgroup 340 should comprise of nodes A93 and A27. The segmentor160 further determined that another optimal subgroup 350 should compriseof nodes A13, A111, and A10. These subgroups 340, 350 may remain on thesame server, may be transferred to different servers, or one subgroupmay remain on the server while the other subgroup is transferred to adifferent server based on existing server loads.

FIG. 6 illustrates a plurality of servers 65 used to host a VU. Morespecifically, FIG. 6 illustrates servers 65 within the VU wherein atleast one server includes one or more subgroups of avatars and/or assetsS1-S6. In the example illustrated in FIG. 6, the costs associated with asubgroup have already been determined and optimal subgroups S1-S6 havebeen formed according to the determination. The subgroups S1-S6 are thensent to the server transfer module (See FIG. 2). The server transfermodule (See FIG. 2) consults the subgroup optimization module (See FIG.2) and receives a list of subgroups S1-S6 to transfer to a secondaryserver. In another embodiment, the server transfer module 28 may obtaina list that requires no transfers to be performed, all subgroups S1-S6to be transferred, or any number of transfers less than the total numberof subgroups S1-S6 on the server. Once the list of subgroups S1-S6 isobtained, the server transfer module 28 transfers the avatars and/orassets to a secondary server. The transfer may be performed using knownVU transferring technology or non-VU transferring technology. In oneembodiment, the transfer may appear seamlessly to the user. In a furtherembodiment, a user may be provided with the choice to transfer beforethe transfer is carried out.

In the example illustrated in FIG. 6, the avatars and assets on server 1have been split into three different subgroups S1, S2, S3. Similarly,the avatars and assets on server 2 have been split into two differentsubgroups S4, S5. In this example, avatars on server 3 have been groupedinto a single subgroup S6, and no subgroups exist on server 4, server 5,or server 6. In the embodiment illustrated in FIG. 6, the servertransfer module 28 will transfer the segmented subgroups S1-S6 to one ormore servers 65. For example, if server one has three subgroups S1, S2,S3, and it is determined by the subgroup optimization module that theserver load on server 1 is disproportionate to the server loads on otherservers hosting the VU, then the server transfer module 28 will transfersubgroups S2, S3 from server 1 to another server. In the exampleillustrated in FIG. 6, subgroup S2 and subgroup S3 are consideredoverload on server 1 and are transferred to server 2. Server 2 alreadyhas subgroup S4 and subgroup S5, which is determined to be adisproportionate load on server 2 as compared to the other servers 65hosting the VU. Therefore, server 2 will not take the load from server 1and the load from server 1 will be transferred to server 3.Additionally, server 2 will try to more optimally apportion its existingload by transferring subgroup S5 to server 4. Once the load from server1 reaches server 3, it is determined whether server 3 can take the loadsuch that server 3 and the other servers 65 hosting the VU will beoptimized.

In this example, it is determined that the load on server 3 would bedisproportionate if subgroup 2 and subgroup 3 were placed on server 3with its already existing load of subgroup S6. Therefore, subgroup 2,and subgroup 3 are transferred to server 5, wherein it is determinedthat server 5 can optimally host at least one subgroup S1-S6. However,since server 6 could also host at least one subgroup S1-S6, the serveroptimization module determines that subgroup S2 should be transferred toserver 5 and subgroup S3 should be transferred to server 6. This seriesof transfers is illustrated in FIG. 6 and the final outcome from thisseries of transfers by the server transfer module 28 is illustrated inFIG. 7. Because different server transfer modules 28 may be used, theactual process of transferring one subgroup S1-S6 to another server maydiffer from this example.

In another embodiment, each transfer by the server transfer module 28 isgiven a transfer cost. A transfer cost may be represented by the amountof resources that are needed to transfer a subgroup from one server toanother server. If the amount of resources to transfer a subgroup toanother server is high compared to the degree of optimization that wouldresult from the transfer, then the optimal outcome may be to foregotransferring the subgroup to another server. Additional embodiments mayforgo transferring a subgroup from one server to another server ifoptimization would be minimum regardless of transfer costs.

A number of alternative embodiments may result from the descriptionabove. For example, in one embodiment the subgroup optimization module28 may be run on a periodic interval (e.g., every five or ten seconds)whereby the estimated computation cost and the estimated communicationcost are combined prior to the segmentor 160. The period interval may bebased on real time measurements or on logical time within the VU.However, in another embodiment, there may be a sudden increase in loadon one or more servers 65 such that re-optimization is needed betweenthe periodic intervals.

FIG. 8 illustrates one embodiment, wherein an overload detection system170 determines if a server is overloaded beyond a predefined thresholdvalue for a predefined time period. The overload detection system 170includes a server monitor 410. The server monitor 410 obtains meteringmessages whenever a metering event ME1, ME2 . . . m+1 occurs. Meteringmessages are sent by one or more of the servers 65 hosting the VU, andinforms the server monitor 410 of a metering event ME1, ME2 . . . m+1. Ametering event ME1, ME2 . . . m+1 may include, but is not limited to,chatting, bumping, sharing, visiting a geographic location, or statingmembership of a particular group. The server monitor 410 obtains themetering events ME1, ME2 . . . m+1, which are then used to determine ifa threshold has been met. A threshold may be set by an administratorbased on any one of a number of factors including memory usage, CPUutilization, etc. A threshold value may be influenced by factorsincluding textures within the VU, geometric information, streamingmedia, etc. If the threshold is met or surpassed for more than thepredefined time period then subgroup determination 435 is performed.Subgroup determination 435 may be extemporaneous and/or based on dataobtained from the threshold values. Upon completion of the subgroupdetermination 435, the subgroups are sent to the server transfer module28 (described above.)

Another embodiment may employ an overload detection system 170 thatengages the server transfer module 28 when the load is nearing thethreshold instead of after the threshold has been met. A similarembodiment may determine that an event is going to happen within the VUthat will cause large computation costs and/or communication costs tooccur. This, in turn, may cause the server transfer module 28 to beengaged so that server load can be better apportioned to account for theupcoming influx in server load.

In alternative embodiments, an avatar may have communication costsbetween himself and another avatar, however, the communication cost maynot be strong enough to keep the avatars together in the same subgroupor to have the avatars moved to another server. If avatars with minimuminteractions are separated into different subgroups, then the refreshrate, i.e., the rate in which images are regenerated on the screen, maybe decreased to a lower computation load on the servers 65. For example,an avatar in a subgroup having a refresh rate of one second will be ableto see changes, actions, and/or fluctuations from avatars or assetswithin its subgroup every second. However, if the avatar is looking atanother avatar or asset outside of its subgroup, then the refresh ratemay be three seconds. This example implies that an avatar would not beable to observe actions by other avatars or assets outside of itssubgroup as fluidly as actions by those inside of the avatar's subgroup.By not having to refresh an avatar's, or asset's, actions as frequently,server load can be decreased.

Alternate embodiments, may have the refresh rate differ if an avatar orasset in a subgroup on one server observes an action coming from anavatar or object on a different server, as opposed to coming from adifferent subgroup on the same server.

Additionally, other embodiments may include a refresh rate that differsbetween avatars or assets in the same subgroup. For example, if thesegmentor (See FIG. 2) determines that the optimal grouping includes asubgroup having three avatars, then the segmentor (See FIG. 2) willgroup those three avatars together. Within that subgroup, a first avatarmay have a strong communication cost with the second and third avatarsrespectively; however, the second and third avatars may rarely if evercommunicate or interact with one another. In this example, a fasterrefresh rate may be used for the first avatar so he can more fluidly seeinteractions with the second and third avatars, whereas, a lower refreshrate may be used between the second and third avatars since theirinteractions are much less frequent and do not need to appear as fluid.One skilled in the art would understand that this is an illustration andmay be applied to multiple avatars and/or assets in a subgroup and thatmultiple refresh rates may be used between avatars and/or assets in thesame subgroup, different subgroups on the same server, and differentsubgroups on different servers.

Other embodiments may permit refresh rates to be faster for one avatarand not for another avatar. For example, if an avatar attends a packedconcert in a VU then a refresh rate of one half second may be used sothat the avatar can fluidly see everything that happens on stage duringthe concert. However, a slower refresh rate of ten seconds may be usedfor the performer seeing the avatar's actions in the crowd. This permitsrefresh rates to be used to decrease server load by not having torefresh the avatar in the crowd as frequently. Further embodiments mayadjust refresh rates differently to decrease server load.

In yet another embodiment, an avatar that has an initially weakcommunication cost associated with himself and another avatar or assetmay increase the communication cost by increasing interactions with theother avatar or asset. New interactions, and likewise new resourceexpenditures, are continuously evaluated and can cause one or moresubgroups to be reapportioned to optimize server load. For example, ifavatar #13 initially bumps into avatar #4 then a certain interactioncost 230 will be assigned; however, this interaction alone may not bestrong enough to cause avatar #13 and avatar #4 to be grouped togetherin the same subgroup. If avatar #13 subsequently starts to chat withavatar #4 then the interaction cost will increase, which in turnincreases the estimated communication cost between avatar #13 and avatar#4. The subgroup optimization module 26 will take this change incommunication cost into consideration when reapportioning and maydetermine that avatar #13 and avatar #4 should be located in the samesubgroup. In another embodiment, the computation cost is continuouslyevaluated in a similar manner.

A further embodiment may include an avatar strengthening hiscommunication cost with another asset. For example, if avatar #13previously test drove car #61, then avatar #13 may increase hisinteraction costs with car #61 by washing car #61, purchasing car #61,or by continuing to test drive car #61. These increased interactioncosts in turn increase the estimated communication cost between avatar#13 and car #61. A similar adjustment in communication costs may occurbetween multiple assets.

In another embodiment, the invention provides a business method thatperforms the process steps of the invention on a subscription,advertising, and/or fee basis. That is, a service provider, such as aSolution Integrator, could offer to decrease server load byautomatically determining subgroups based on object interactions andcomputational expenditures. In this case, the service provider cancreate, maintain, support, etc., a computer infrastructure that performsthe process steps of the invention for one or more customers. In return,the service provider can receive payment from the customer(s) under asubscription and/or fee agreement and/or the service provider canreceive payment from the sale of advertising content to one or morethird parties.

While the invention has been described in terms of embodiments, thoseskilled in the art will recognize that the invention can be practicedwith modifications and in the spirit and scope of the appended claims.

What is claimed is:
 1. A system for reducing server loads, comprising: aplurality of servers; a subgroup optimization module configured to:assign respective costs to interactions amongst a plurality of objectsin a virtual universe; and segment the plurality of objects intosubgroups based on the respective costs of the interactions; and aserver transfer module configured to apportion one or more of thesubgroups between the plurality of servers, wherein the assigning therespective costs to the interactions comprises assigning one of aplurality of unit values to each of the interactions, and wherein eachof the plurality of unit values are based on interaction importance andinteraction length.
 2. The system for reducing server loads of claim 1,wherein the plurality of objects include at least one of a plurality ofavatars and a plurality of assets.
 3. The system for reducing serverloads of claim 1, wherein one or more of the interactions are real-timecommunications between two or more of the plurality of objects.
 4. Thesystem for reducing server loads of claim 1, wherein the subgroupoptimization module further comprises a communication cost estimatorconfigured to assign respective communication costs to the interactions.5. The system for reducing server loads of claim 4, wherein thecommunication cost estimator is further configured to determine therespective communication costs assigned to the interactions based onrespective characteristics of the interactions.
 6. The system forreducing server loads of claim 1, wherein the subgroup optimizationmodule is further configured to: assign a respective communication costto the interactions based on respective characteristics of theinteractions; and determine a total communication cost for a linkbetween a first object and a second object based on the respectivecommunication cost of one or more of the interactions that involve thefirst object and the second object.
 7. A method for reducing serverload, comprising: determining interactions amongst a plurality ofobjects in a virtual universe; assigning respective interaction costs tothe interactions; segmenting the plurality of objects into subgroupsbased on the respective interaction costs; and apportioning one or moreof the subgroups between a plurality of servers based on a load of eachof the plurality of servers wherein the interactions are assigned unitvalues that are based on (i) importance of the interactions, (ii) lengthof the interactions, and (iii) when the interactions occurred.
 8. Themethod for reducing server load of claim 7, wherein the plurality ofobjects include at least one of a plurality of avatars and a pluralityof assets.
 9. The method for reducing server load of claim 7, whereinone or more of the interactions are real-time communications between twoor more of the plurality of objects.
 10. The method for reducing serverload of claim 7, wherein the assigning the respective interaction coststo the interactions comprises assigning a respective communication costto the interactions.
 11. The method for reducing server load of claim10, wherein the assigning the respective communication cost to theinteractions comprises determining the respective communication costsbased on respective characteristics of the interactions.
 12. A computerprogram product comprising a computer-readable storage device havingreadable program code stored on the storage device, wherein the computerprogram product includes at least one component operable to: determineinteractions amongst a plurality of objects in a virtual universe;assign respective interaction costs to the interactions; segment theplurality of objects into a plurality of subgroups based on therespective interaction costs; and apportion one or more of the pluralityof subgroups between a plurality of servers based on a load of each ofthe plurality of servers, wherein the interactions are assigned unitvalues, the computer-readable storage device comprises one of: amagnetic tape, a removable computer diskette, compact disk-read onlymemory (CD-ROM), compact disk-read/write (CD-R/W) and DVD, and the unitvalues depend on (i) importance of the interactions, (ii) length of theinteractions, and (iii) when the interactions occurred.